It was the final question of the last post-match press conference of the autumn series. "Stuart, if you could add one extra thing to your side, what would it be?"

"Manu," was Lancaster's response, referring to the Tigers centre who missed the four internationals through injury. The answer was a single word, but one sat atop an increasingly sizeable iceberg. Then the clarification: "He is a world-class player. There are others as well obviously - if you are to win the big games then you need your world-class players and he is in that category".

Moments earlier Lancaster had extolled the virtues of the centre partnership fielded in England's final Test against Australia - Billy Twelvetrees and Brad Barritt. It was the third different starting combination used during the four autumn internationals, yet it was the absent Leicester centre who remains Lancaster's missing link.

"England have experimented with the x-factor option at inside centre in Eastmond but expect to see a return to the fire and brimstone of Barritt and Tuilagi come the Six Nations"

Of all the areas in England's team, just who wears No.12 and No.13 poses more questions than answers. When asked about the options at his disposal ahead of the Six Nations, Lancaster name-checked Tuilagi, Owen Farrell, Luther Burrell and Kyle Eastmond alongside the duo who started against the Wallabies.

Then there is the ex-rugby league elephant in the room who touched the ball twice on Friday night against Harlequins. "It was a good carry, wasn't it?" was Lancaster's assessment of Sam Burgess' Bath debut. "He is one who will be of interest, without a doubt. It took about three men to stop him. I don't know what he made he made of the scrum thing - the three yellow cards - but he is a powerful man and it will be nice to see him get a few more games and put his hand up."

A potential opportunity with the Saxons in their January match was also dangled in front of Burgess' nose. He is already on the radar.

Tuilagi, Burgess, Twelvetrees, Barritt, Eastmond, Burrell, Farrell, Jonathan Joseph and Henry Slade - nine names in contention for two spots on Lancaster's team sheet. It is a difficult juggling act and with the games between now and the World Cup in single digits, the balls Lancaster is attempting to keep airborne seem to be increasing.

That decision will be easier when England settle on a strategy for the World Cup. The June Tests saw them attempt to out-Kiwi the All Blacks as they threw the ball around in the backs in a bid to add another dimension to one which sees the forwards punch the holes. It did not work, and after further attempts to marry the two styles in the first two games of the autumn, they reverted to forward ballast against Australia.

If that is to be the game plan for the World Cup then Barritt fits the ethos, with Tuilagi potentially alongside him. We have only seen 17 minutes of Burgess, but if this is the avenue England want to go down he too has the physical standing to feature though his reputation will not be enough for Test recognition. He has to hit the ground running.

The Bath midfield is a much-admired combination, with Eastmond and Joseph encouraged to play the game at high tempo with offloads at the forefront. That England made just 18 offloads in their four autumn internationals suggests Lancaster will be looking for the centres to get over the gain line through brute force rather than sleight of hand. Eastmond, Joseph and Slade would therefore be left to watch the World Cup from their respective sofas.

Despite this tendency, Lancaster claims England's centre partnership is not about prioritising defence over attack. "You certainly need someone who can defend well at 13. Going into the series, with Manu and Luther being injured, Barritt was the stand-out player. We could have gone for Joseph, but look at Barritt's contribution [against Australia]. It's not favoured one way of the other. We have two exciting wingers now and we don't want just to defend all the time, we want to score tries. Of the 26 tries prior to today, 21 were by the backs, 13 by the back three. I don't think we are a one-trick side in terms of defence."

With eight games until the World Cup, the smart money will be on Lancaster reverting to a tried-and-tested game plan for the Six Nations. The forward dominance they showed against Australia on Saturday was a hark back to their performance in the 2007 quarter-final and the capitulation the Wallabies suffered two years previous. Those bright young things Anthony Watson and Jonny May are likely to stay on the flanks for the Six Nations but they should not expect many offloads from the centres.

England have experimented with the x-factor option at inside centre in Eastmond but expect to see a return to the fire and brimstone of Barritt and Tuilagi come the Six Nations. It could yet be the ideal game plan for the man who watched Saturday's game from the stands - one Sam Burgess.